a=ones(1,101);
for n=length(a):(-1):1
    if rem(n,2)==0
        a(1,n)=-1;
    end
end

%enallaktika
% for n=2:2:length(a)
%      a(1,n)=-1;
% end

polyval(a,[1,0,-1])
polyder(a)
polyint(a)
